1. Field of the Invention
The present invention relates to an unwinding apparatus for unwinding a tape-like sheet.
2. Description of Related Art
There is used a ribbon cassette receiving an ink ribbon in a winding state for a printer for printing on a recording paper by a heat transfer and the like. Also, there is used a tape cassette receiving a magnetic tape in a winding state for an audio equipment, and further, there is used a tape cassette receiving a video tape in a winding state for a video apparatus. These ribbon cassette and tape cassette are loaded into respective equipments, thereby a printing, a recording and a playback of a voice and an image and the like are carried out.
By the way, in a conventional printer of a type in which a printing is performed on the recording paper, among these apparatuses, a ribbon cassette provided therein with a tape-like ink ribbon is inserted into an apparatus main body through a cassette inlet and outlet opening formed on a side portion of the apparatus main body, and the inserted ribbon cassette is set at a predetermined position of the apparatus main body. After that, when a head attaching member disposed movably in upward and downward directions to the apparatus main body is pressed down, the printing head disposed on the printing attaching member is inserted into the ribbon cassette through an upper opening member formed on the ribbon cassette. Then, since a platen is arranged at a position opposed to the printing head, the printing head is abutted to the platen through the ink ribbon and the recording paper. Under such a circumstance, a winding motor is driven to rotate a winding shaft for winding a ribbon disposed in the cassette. A printing signal is supplied to the printing head while winding the ink ribbon by the rotation of the winding shaft, then an ink formed on the ink ribbon is transferred to the recording paper to perform a printing by heat-generating and driving an exothermic element disposed on the printing head.
In case of the conventional printer having such a construction, as described above, the head attaching member is rotated downward after the ribbon cassette is loaded, then the printing head disposed on the head attaching member is entered into the ribbon cassette through the upper opening portion formed on an upper portion of the cassette, and further the printing head is press-contacted to the platen through the ink ribbon and the recording paper. However, since the platen is arranged below a position of the lower opening portion formed on a lower portion of the cassette, the printing head entering into the ribbon cassette is pressed down to below the position of the lower opening portion of the cassette. Accordingly, a portion of the ink ribbon to which the printing head abuts is protruded outwardly from the lower opening portion of the ribbon cassette.
On the other hand, in order to take out the ribbon cassette from the apparatus main body, the head attaching main body is moved upwardly to cause the printing head to retreat from an inside of the ribbon cassette, and then, the ribbon cassette is taken out outward from the cassette inlet and outlet opening formed on the side portion of the apparatus main body. At that occasion, as described above, since one portion of the ink ribbon is maintained to be protruded outward partially from the lower opening portion of the ribbon cassette, the protruding portion of the ink ribbon is caught by a lower edge of the cassette inlet and outlet opening, and a chassis or electronic parts and the like in the apparatus main body, there is a case that the ribbon cassette cannot be taken out therefrom. In order to prevent such a matter, conventionally, the unwinding shaft for unwinding the ink ribbon and the unwinding motor are connected to each other, and the motor is driven in connection with the upward movement of the head attaching member to rotate the unwinding shaft in the unwinding direction for the ink ribbon. Thereby, the ink ribbon is unwound to eliminate a protruding portion, that is, a dip portion of the ink ribbon. Then, the ribbon cassette is caught by the lower edge of the cassette inlet and outlet opening, or the chassis or the electronic and the like in the apparatus main body, so that the ink ribbon is taken out smoothly and rapidly.
However, in such conventional printer, since the tape-like ink ribbon is unwound by the driving of the motor disposed in the apparatus main body, the unwinding of the ink ribbon cannot be performed in a case where the motor is out of order, the driving circuit of the motor is disconnected, or the electric power for driving the whole apparatus is off. Accordingly, the protruding portion, that is, a dip portion of the ink ribbon cannot be eliminated, there is a problem that the ink ribbon cannot be taken out from the apparatus main body smoothly and rapidly.